The present invention relates to video display systems, and more particularly, to using on-screen menus in adjusting multi-frequency cathode ray tube (CRT) displays.
Video displays incorporating CRT systems provide information to and receive information from computer systems. The versatility of CRT systems, and the variety of ways they display data, have ensured their widespread use. Early video displays typically were single-frequency displays: the video adaptor card that operated the display (by sending information from the computer to the display) used a single horizontal scanning frequency tuned to that of the display. A card fabricated for a particular single-frequency display often will not work with other displays. Multi-frequency video displays represent an important improvement in video display technology, for a single display system can be attached to a wide variety of video adaptor cards. The multi-frequency display can tune itself to the horizontal frequency of the attached adaptor card, and synchronize the display to the information sent from the adaptor card.
While multi-frequency displays provide a great improvement over single-frequency displays, and allow versatile connections of displays and adaptor cards, these displays exacerbate problems common to video displays in general. Most video displays provide some form of adjustments for users. Typically, a panel of knobs and buttons connected to potentiometers or other electrical switches allow the user to adjust various display characteristics. Contrast, brightness, and the horizontal and vertical image positions are some of the possible adjustments one can make. Since these adjustments are made manually using electromechanical devices, the adjustments are susceptible to slight shifts over time. Movement of the display, changes in ambient temperature and environmental vibrations can all alter carefully set adjustments.
Multi-frequency displays that incorporate electromechanical user adjustments share these problems of misadjustment. In addition, these displays multiply adjustment problems for each new frequency mode available. Each time a user changes the frequency mode used by the monitor, all the adjustments made previously must be readjusted to compensate for changes in the display. Furthermore, once these changes ;ire adjusted, they again become susceptible to slow misadjustment.
Multi-frequency displays present further manufacturing difficulties. In addition to user-operated external controls, each video display possesses a number of internal controls that precisely adjust the display. These internal controls are preset at the factory by a human operator comparing the display against a standard. To ensure comparable operation across frequency modes, multi-frequency displays often hive separate sets of these adjustments for each of several principle frequency bands. Each of these adjustment sets must then be hand-adjusted by a factory operator. Again, the electro-mechanical nature of the controls allows for gradual drift in their adjustment.
Current methods for adjusting, video displays, particularly in multi-frequency systems, do not provide a complete and flexible system for allowing users and manufacturers to quickly and reliably set display controls. What is needed is an improved method and apparatus for adjusting, video displays. An improved video display adjustment apparatus and method should allow the factory to quickly set all internal controls for a monitor, without operator intervention. The improved apparatus and method should also allow end-users to easily change display characteristics, or reset the characteristics back to those specified at the factory. The method and apparatus should also maintain the video display characteristics despite thermal, mechanical or other environmental changes. The improved method and apparatus should provide techniques and apparatus applicable to a wide range of video display devices, including CRTS, LCDs and electro-luminescent displays. The invention should provide a simple and cost-effective technology for easily and accurately changing and maintaining the characteristics of any video display.